A Case of the Greater Omental Hemorrhage due to Segmental Arterial Mediolysis

The case is a 58-year-old male, who was receiving inpatient care at a neighborhood hospital due to upper abdominal pain and diarrhea. Since accumulation of a large amount of abdominal dropsy in the whole abdomen as well as hematoma within the greater omentum was recognized as a result of abdominal CT, he was diagnosed with intraperitoneal hemorrhage caused by bleeding from the greater omentum. Angiographic examination of the abdomen did not indicate clear leakage of contrast medium outside of blood vessels in the greater omental artery branched off from the intrasplenic artery; however abnormal expansion and meandering of blood vessels as well as filling defect within some blood vessels was recognized and considered as the bleeding source. Arterial embolization did not realize hemostasis, and he was transferred to our clinic to perform emergency surgery on the same day. Accumulation of a large amount of blood in the abdominal cavity as well as hematoma in the greater omentum was recognized and other bleeding sources were not identified; therefore he was diagnosed with hemorrhage from the greater omental artery and underwent partial resection of the greater omentum. Histopathologic findings indicated failure of aneurysm walls in the greater omental artery, and survival of island-shaped media on the aneurysm walls as well as significant vacuolation of smooth muscle cells in the media; therefore failure of the greater omental artery was diagnosed due to segmental arterial mediolosys.